Human embryonic stem cells (hESC) for hematopoietic and HIV/AIDS therapies Human embryonic stem cells (hESC) show great promise for novel cell replacement therapies due to their capacity to give rise to any type of cell in the body and their tractability for genetic modification. Currently, CD34 hematopoietic progenitor cells (HPC) obtained from non-renewable sources such as bone marrow and cord blood are used for clinical applications. The recent demonstration that CD34 hematopoietic progenitor cells (hES-CD34) could be derived from hESC opened up many exciting possibilities for their use in hematopoietic cell and AIDS therapies. As a first step towards this goal, we succeeded in our recent efforts in deriving functionally normal macrophages and dendritic cells from hES-CD34 cells and showed that they are susceptible to HIV-1 infection thus paving the way for testing various anti-HIV gene therapeutic constructs in this system. Due to the lack of an ideal animal model, a thorough assessment of the multi-lineage hematopoietic capacity of hES-CD34 cells in vivo has not been possible. A novel humanized mouse model (RAG-hu) has emerged recently that permits such an evaluation, and we have this system currently established in our laboratory. We also identified a number of new generation anti-HIV gene constructs with high efficacy in our ongoing gene therapy studies. These new developments laid a good foundation to evaluate the utility of hES-CD34 cells for gene modification, multi-lineage hematopoiesis and HIV gene therapy strategies. In this proposal our aim is to exploit the newly emerging technologies and build upon our recent progress towards translating hESC derived cells for clinical applications. The specific objectives of our proposal are to: 1. Genetically program hESC with anti-HIV genes and derive HIV-1 resistant mature hematopoietic end stage cells. 2. Evaluate the multi-lineage hematopoietic differentiation capacity of hES-CD34 cells in Rag2-/-3c-/- mice. PUBLIC HEALTH RELEVANCE: Human embryonic stem cells show enormous promise for developing novel cell replacement and gene therapies. In these proposed studies, anti-HIV genes will be introduced into stem cells to derive virus resistant white blood cells. Success of this work would not only benefit HIV/AIDS field but also will have broader implications for hematopoietic cell therapies and transplantation.